69 



LoHNis: Excess of Manganese 



Figure 1 1 presents a few values for oats, the content in man- 

 ganese of which in the most acid plots exceeds only slightly the 

 value found in the most strongly limed plots. The tolerance of 

 oats for injury by excess of manganese appears to be due to their 

 low intake. This may also explain the susceptibility of oats for 

 the "grey speck disease" caused by a manganese deficiency. 



soc 



I 



I 



I 

 r 



i 

 i 

 I 



I 



AS 



Textfigure 10.— Manganese content of foliage of a niunber of crops 

 grown on the same plot C1946). 



Will soils, varying in causing injury to beans, vary also in 

 content of plant available manganese? To answer this question 

 I determined the exchangeable manganese in soil samples follow- 

 ing the method developed by Heintze (1): — 



5 g Soil are mixed for one hour with 100 ml N CaCN03)2 

 and then filtered off. Manganese is analyzed in the filtrate. 



